1. Field of the Invention
This invention relates generally to the capping of gushing wells whether or not such wells are on fire, fire extinguishing and flow control apparatus and method particularly adapted for use in capping wells whose products are both gushing and on fire, and controlling the flow from such wells.
2. Description of the Prior Art
A variety of oil well fire extinguishing apparatus have been employed in the art. Several major variations differentiate the apparatus taught by the prior art.
Cones or domes or other inverted containers of various sorts have been suggested as housings to be placed over uncontrolled wellheads to stop both the flow and combustion of escaping oil. The apparatus include those designed to contain the flow from one on-shore well (Howe U.S. Pat. No. 1,830,061; Featherstone U.S. Pat. No. 1,520,288), and similar designs with valves to control the flow of oil once the protective hood is in place above the broken wellhead (Sievern U.S. Pat. No. 1,859,606; Teed U.S. Pat. No. 1,807,498). Similar apparatus have been suggested to contain the flow of escaping oil from offshore wells at the ocean floor (Lunde U.S. Pat. No. 4,318,442).
Other designs seek to enclose entire on-shore oil tanks or wells in order to smother flames and contain uncontrolled oil flow (Cunningham U.S. Pat. No. 4,433,733), or offshore platforms (Chiasson U.S. Pat. No. 3,815,682; Roy U.S. Pat. No. 3,730,278; Chiasson U.S. Pat. No. 3,724,555).
Some of the above mentioned patents are designed only for extinguishing fires and do not provide for the control of the well product after the flames are extinguished. While these devices may be effective when the well contents are not under substantial positive pressure, they do not provide a complete solution for the control of fires on pressurized well heads.
The primary problem with cone or dome designs employed to extinguish fires and control the flow of a pressurized well head is that of preventing the escape of well product around the base of the cone or dome. Some designs rely on the weight of the cone or dome and the firmness of the ground around the well pipe to accomplish this sealing. E.g., Sievern, U.S. Pat. No. 1,859,606 (also employing hooks on the sides of the dome from which could be mounted guy wire anchors for further sealing of the cone against the ground). Others employ the pumping of cement or other adhesive into the dome to obtain a good seal after such adhesive hardens. Teed, U.S. Pat. No. 1,807,498. Still others require that the well head already be mounted in a slab contoured to fit tightly within the dome or cone. Howe, U.S. Pat. No. 1,830,061. Still others require some surface preparation, such as construction of a dike around the well, at the time of employment of the fire extinguishing and capping apparatus. Murphy, U.S. Pat. No. 1,857,788.
None of these devices solves the problem of adequately controlling the flow of pressurized well product. The prior preparation of the ground to receive an extinguishing cone prior to a blowout or other problem is expensive. Furthermore, domes heavy enough to effectively stem the flow of product in highly pressurized wells are unwieldy and expensive to use, especially in remote locations. Evidence of these and other drawbacks to such designs is the lack of use of such designs in fighting well fires despite the fact that they have been known in the art for many years.
Some apparatus seek to divert flames and flow of oil by means of a length of pipe placed around, into, or over the broken wellhead (Nicolesco French Pat. No. 1,219,418; Patton U.S. Pat. No. 2,082,216; Wapanob U.S.S.R. Pat. No. 955,945; U.S.S.R. Pat. No. 903.561; Fleischmann U.S. Pat. No. 1,921,739; Collins U.S. Pat. No. 1,938,009). Such apparatus have a flaw analogous to that described above for domes and cones. Most of these diversion apparatus fail to solve the problem of obtaining an adequate seal between the diversion pipe and the well pipe. Thus, they also fail to control the flow of product from pressurized well heads. Neither the Collins device nor the Fleischmann device adequately address the problem of escaping, pressurized well product.
Two devices to deal with sealing the device to the well pipe in a manner which might create a sufficient seal to prevent the undesired escape of pressurized well product. The Teed patent, and the Patton patent. Teed and Patton are discussed in more detail below.
Although apparatus which fail to obtain complete diversion and prevent the escape of pressurized well product may reduce the flames to the point where the fire can be controlled and the well capped by other means, they do not leave the well in a state where production can be quickly and economically resumed. Therefore they provide at most an incomplete solution to the problem.
The Teed patent, U.S. Pat. No. 1,807,498, discloses an extension/diversion pipe connected to a double-walled containment cone or dome and thus, the device would be a hybrid in the classification scheme presented above. The Teed device purports to solve the problem of well product escaping around the base of the cone by pumping an adhesive into the cone in an attempt to cement the cone base firmly to the well pipe.
It employs a product diversion means similar to those in the current invention; however, the adhesive sealing means it employs is very different from the current invention. The device is essentially comprised of a wider and a narrower concentrically disposed cones both attached to one end of a pipe the other end of which is attached to a coupling to which is attached a controlled, vertical "flame pipe" which acts as an extension tube to remove the flaming product from the end of the well pipe to the end of the flame tube, and at least one controlled, horizontal "lead off pipe." The double cone construct is also fitted with two feed tubes, one extending through the inner cone and opening into the interior cone chamber, the other extending only through the outer cone and opening into the outer cone chamber. It appears from the disclosure that the device is to be lowered over the gushing or flaming wellhead with the valve to the flame pipe opened thereby diverting the flame or flow vertically away from the wellhead. Cement or some other adhesive is to be pumped into the inner and outer cone chambers below the wellhead sealing off the flow from the bottom and further forcing the flow upward through the flame pipe. Once the cement has set, the flame pipe valve can be closed and the device capped. Well product can then be diverted into a lead off pipe by opening a lead off pipe valve. The controls on the flame pipe and the lead off pipe are valves which are attached to pulley actuators which are capable of being remotely actuated by pulley belts.
Like the current invention, the Teed patent teaches the use of a controlled extension tube or pipe attached to an apparatus which is fitted over and attached to an uncontrolled, possibly flaming well. Any fire is extinguished primarily by controlling the flow of product with the flame pipe valve. Furthermore, like the current invention, the Teed patent teaches the use of remotely actuated valves. The Teed patent suggests use of pulleys and belts of sufficient length to allow actuation of the valves from a safe distance, while the current invention suggests use of more fire resistant sprockets and chains of sufficient length to allow for safe, remote operation.
The principal differences between the current invention and the Teed apparatus relate to the method of fixing the apparatus to the well pipe. While I do not know whether the Teed method of fixing the device to the well head by use of the cone and pumping in a cement type sealing adhesive has been successful, I believe that the device taught by the Teed patent has not been commercially successful. I believe that the major drawback of the Teed device is the failure of its mechanism for finding the apparatus to the well pipe. In order to work properly the sealing mechanism must be able to complete the seal around the base of the wellhead despite the pressure from the flowing wellhead. It is my belief that the pressure from the gushing well prevents successful sealing by the use of concrete or other adhesive pumped into the Teed double cone construction. Such pressure, even if primarily diverted up through the flame pipe, would still be sufficient to force the wet cement or other adhesive out the bottom of the cone. Furthermore, the Teed device has no mechanism which would force the device into the ground surrounding the wellhead with sufficient force to overcome the wellhead pressure. It must depend on its weight alone to withstand that portion of the wellhead pressure which is not diverted up the flame pipe. Furthermore, even if the inverted dome were forced into the ground around the wellhead, the sealing cone would only be effective where the ground surrounding the wellhead was sufficiently level and firm to prevent the escape of wet cement and well product. Furthermore, in order to work, the Teed device requires the availability of an adhesive, such as concrete, which will remain in its viscous, semisolid state while being pumped into the cone chambers, despite the heat generated by the fire, and then harden. Although a successful diversion of the well flow away from the wellhead up the flame pipe would reduce the flame and heat at the wellhead, the diversion would not be successful until the cones were fully sealed. Therefore, at the time of the introduction of sealing adhesive, there is likely to be significant flame and heat at the wellhead. Finally, even if the device works under real life conditions, the amount of equipment and materials required to operate the device makes it less useful in remote or hostile environments. Wet cement might freeze before use on the Alaskan North Slope. The amount of water needed to mix the cement and the resulting logistical requirements may be a problem in desert conditions. The timing of the mixing of a hardening adhesive, such as cement, might also be a drawback, if the progress of mounting the device could not be accurately predicted. The current invention overcomes all of these drawbacks.
The Patton Device, like the Teed device, employs an extension tube to remove the flame from the well pipe end. The Patton device fixes the extension tube directly to the well pipe by forcing a tapered nozzle into the well pipe and then clamping the nozzle to the well pipe by means of a clamp. The juncture of the nozzle and the well pipe is made leak proof by the introduction of a "liquid sealing material" into the nozzle pipe and through the nozzle pipe into the well head pipe. The extension tube is controlled, fitted with a nozzle with a tapering diameter which is small enough in diameter at the end to fit inside the well head pipe. The suggested method is to position the device over the well head, use a built-in diverting shield to displace the flow of product/flame to the side, force the tapered nozzle into the end of the well pipe and then, once the flame is transferred to the end of the well, clamp the junction of the nozzle and the well pipe together. A liquid sealant is then pumped into the nozzle pipe and forced down into the well pipe where it should seal the junction, forming a permanent seal. The control valve on the flame pipe may then be closed extinguishing the fire.
The drawbacks to the Patton device are several. First, it is difficult to force a pipe of smaller diameter (the nozzle) into a well pipe from which is flowing pressurized and burning well product. Second, it may be difficult to find a sealant which can be pumped into the nozzle, and forced, against the well pressure, down the nozzle and into the junction between the nozzle and the well pipe. Third, the construction of the device does not allow the entire extinguishing job to be accomplished remotely. Workers must bolt the clamp to the junction of the nozzle and the well pipe prior to closing the flame pipe valve.
Despite the wide variety of oil well fire extinguishing apparatus existing in the art to date, as exemplified by the above-discussed designs, there is a continuing need for an improved oil well fire extinguishing and flow control method and apparatus which is easily transported, can be quickly deployed, is structurally and operationally adapted to perform in the hostile environmental conditions, controls the flow of escaping well product, extinguishes combustion quickly, can be remotely operated, and, upon extinguishing the fire and controlling the flow, facilitates prompt resumption of controlled production from the well. However, the prior art does contain adequate solutions for several critical steps in controlling well fires. Means for remotely directing and lowering devices over well pipes are well known. They include use of cranes, booms and positioning cables. Means for remotely activating valves are also well known, including use of chains and sprockets as well as cables or belts and pulleys. Further, remote use of high temperature tolerant hydraulic actuators can be employed to perform many functions involved in the extinguishing of fires, such as the actuation of valves, as well as lowering and raising devices and actuating clamps. Finally, there are many sealing materials which are sufficient to obtain a leak-proof seal around a sealing joint. Various packing and sealing materials are available and are employed by the oil and gas industry which are insoluble in well product, inflammable, temperature tolerant and plastically deformable.
Many well fire extinguishing apparatus simply have not proven themselves in actual service. Current oil well fire extinguishing methods and apparatus actually in use require excessive materials or time before control of the wellhead is achieved and are dangerous to perform or operate. In addition, current oil well fire extinguishing methods and apparatus do not facilitate the simplified resumption of controlled production from the controlled well.
Accordingly, it is a primary object of the present invention to provide, in the manner hereinafter set forth, a method and device whereby a gushing well may be expeditiously extinguished and capped regardless of whether or not the product gushing from the well is on fire.
A further object of the present invention is to provide a method for extinguishing well fires in gushing wells and controlling flow which includes lowering and clamping of a diverting and sealing apparatus to the existing wellhead to divert the gushing well product from the wellhead through the apparatus, sealing the apparatus to the existing wellhead pipe, and closing a valve in the apparatus which controls the flow and extinguishes any product fire by such control.
A further object of the present invention is to provide a device which is simple in construction, inexpensive to manufacture, highly mobile, and capable of being quickly and effectively deployed in hostile environments using a minimum of resources.
It is another object of the present invention to provide an oil well fire extinguishing method and apparatus which allows for the control of the flow of escaping oil and gas and halts combustion quickly while allowing for the safety of the operators and facilitating the timely resumption of controlled production from the well.
It is another object of the present invention to provide an oil well fire extinguishing method and apparatus which greatly reduces the logistical problems inherent in extinguishing oil well fires in remote or hostile environments due to its highly transportable nature and to a reduction in the amount of on-site preparation and material requirements.
It is a still further object of the present invention to provide for a method and device for extinguishing wellhead oil fires and controlling the flow of oil by remote operation.
Other objects and advantages of the present invention will be more fully apparent from the ensuing disclosure and claims.